For dam, embankment, sluice, aqueduct, culvert pipe, channel and other water-adjacent structures, the fast and reliable monitoring of structure health is of great significance to find out safety hazards in time and ensure the safety service of the water-adjacent structures. With the development of distributed optical fiber sensing technologies, to acquire the structure property information and sense the health conditions of the structures by means of the technologies has become an important research direction in the engineering safety field of water conservancy and civil engineering, which has obtained rich theoretical achievements and accumulated a lot of valuable practical experience. However, there are still many technical problems that need to be solved and improved due to the particularity of the working environment and structural characteristics in the actual water-adjacent structure application.
Traditional point monitoring equipment and technologies have corresponding monitoring specifications and processes mostly, but there are no clear and mature operations and use provisions regarding water-adjacent structure health sensing distributed optical fibers; and particularly, the length of the optical fiber used in actual water-adjacent structure health sensing is up to thousands of meters sometimes, and the weight thereof is up to several hundred of kilograms, and there is still lacking of necessary solutions and measures for the calibration problems that affect the monitoring stability and precision thereof.
In the application of monitoring a sensing optical fiber longer than 100 meters, one or a few segments of the optical fiber are calibrated at present on the basis of segmentation calibration by means of a regular thermometer, with the average value of the temperature coefficient of the segment selected as the temperature coefficient of the entire sensing optical fiber. The precision will be constantly reduced with the increase of the length of the sensing optical fiber, and the method has the disadvantages of low calibration efficiency, short calibration length, low load weight, difficulty in cooling and cooling, and uneasy control of temperature. The long-distance wide-range effective calibration problem becomes one of the important obstacles to apply and promote the distributed sensing technology in the actual engineering of the water-adjacent structure health sensing in large scale. It is desirable to research and development a novel water-adjacent structure health sensing distributed optical fiber calibration system and a method with the advantages of long calibration distance, big load capacity and high precision and efficiency.